etc. But this leads to a poor UX for the users. Here is the link for that answer; html - Protect image download - Stack Overflow
], although this is for images but the concept is same for other files too.
A good approach is to trust the users with the content and do not expect anything else, and I highly recommend letting the users download or print the PDF
because that way they trust your website and are likely to return and support your business model.